On June 18, 1855, the first ship passed through the Soo Locks, located on the St. Mary’s River between Lake Superior and Lake Huron. Today there are four locks, and an average of 10,000 ships pass through them each year.
On May 28, 1937, the Golden Gate Bridge officially opened to traffic. It was the longest suspension bridge in the world at the time of its opening and was dubbed a “Wonder of the World” structure.
On May 24, 1844, Samuel Morse sent the first message over telegraph. While in the Supreme Court chamber of the US Capitol, he sent the message “What hath God wrought!” over the telegraph to his assistant in Baltimore, Maryland.
Inventor Ottmar Mergenthaler was born on May 11, 1854, in Hatchel, Kingdom of Württemberg (present-day Baden-Württemberg). Mergenthaler invented the linotype machine, which made it quicker and easier to set complete lines of type for printing presses, revolutionizing printing in the 19th century.
On May 3, 1911, Wisconsin passed America’s first worker’s compensation program. This law provided financial security for workers injured on the job. By 1948, all the then-48 US states had passed such laws. Alaska and Hawaii had workmen’s compensation laws when they joined the Union.
The first continuously-published newspaper in the American colonies, The Boston News-Letter, published its first issue on April 24, 1704. It was the only continuously-produced paper in the colonies for 15 years and ceased publication in 1776 due to the American Revolution.
Apollo 16 launched from the Kennedy Space Center in Florida at 12:54 p.m. on April 16, 1972. It was the 10th crewed Apollo mission and the fifth and second to last to land on the Moon.
Mathematician and electrical engineer Charles Proteus Steinmetz was born Karl August Rudolph Steinmetz on April 9, 1865, in Breslau, Province of Silesia, Prussia (present-day Wrocław, Poland). Steinmetz developed the electrical theories that allowed for the expansion of the electric power industry. He was also known as the “Forger of Thunderbolts” and the “Wizard of Schenectady.”